The present invention concerns an automatic separator to separate a print support from the related supporting sub-layer wherein the print support is normally constituted by a base material used to print circuits in microelectronics and to make up multi-layer circuits.
An example of this print support is typically the so called green tape, which is a Du Pont(copyright) trade mark and material. However, there are other materials in the state of the art which perform the same functions or analogous functions.
The present invention also concerns the method to obtain circuits for microelectronics on a print support.
In the following description the term print support means any support, made of any material whatsoever, which serves to print circuits in microelectronics and to make up multi-layer circuits.
Likewise, the supporting sub-layer, which serves to hold the print support in the correct position and in the desired size, can be made for example of Mylar, P.E.T. or other material suitable for the purpose.
It should be remembered that the print support, within very narrow tolerances, has to keep its size and the reciprocal position of the holes and the printed parts until the various specialized supports have been assembled, which assembly fixes the whole thing, also in relation to the other supports.
It should also be remembered that the materials which make up the print supports, which have a thickness varying from 0.008 mm to 0.30 mm, are affected by even the smallest stress, whether it be heat or mechanical stress, so that, if they are not handled with particular care, at the moment the supporting sub-layer is detached from the print support, they modify their size.
It is therefore important to be able to perform all the necessary operations on the print support keeping the supporting sub-layer and removing it at the last moment, that is to say, a short time before the print support is assembled with other specialized print supports.
The invention is therefore applied to already cut print supports with the relative supporting sub-layer, before any operation is started thereon, in squares or rectangles or other shape of limited size, already holed and printed and ready to be assembled or positioned on the application plane.
The invention also comprises the method to perform all the operations of holing, centering, printing and handling the print support, since the latter is combined with the supporting sub-layer.
At present the supporting sub-layer is detached when the print support is still wound in a roll.
This creates subsequent problems in handling the print support cut into squares or rectangles or into other shapes of limited size, since the print support is not stable during the operations of holing, centering, printing and handling.
Document U.S. Pat. No. 5,466,330 discloses a handling apparatus for ceramic green sheets, wherein for separating the carrier films from the ceramic green sheets, which are prepared for manufacturing a ceramic multilayer circuit board, each ceramic green sheet is maintained in a rest position by a stationary attracting head. The separation is obtained by gradually removing the carrier film by means of a chuck which is movable with respect to the stationary attracting head starting from an end of the ceramic green sheet.
IBM Technical Disclosure Bulletin Vol. 23, No. 4, September 1980, W. Cole et al, discloses a mechanism for peeling paper from green sheets, wherein a vacuum transfer head picks up the top green sheet and the underlying paper sheet and transfer them to the screening station. The backing paper is then peeled off the underside of the green sheet by means of a gripping mechanism which firstly grips the lefthand edge of the paper backing sheet and then is lowered at a short distance with respect to the vacuum transfer head.
Document JP-A-03218802 discloses a film peeling device wherein a green sheet is placed on a given position on a stationary jig and vacuum sucked. One end of the film to be removed is clamped between two rollers which are moved at a constant speed with respect to the stationary jig, so that the film is peeled from the surface of the green sheet.
The invention is set forth and characterized in the main claims, while the dependent claims describe other innovative features of the invention.
According to the invention, the work elements, each constituted by a print support and the related supporting sub-layer, are normally cut in a square shape, but also in other shapes, from a roll consisting of the print support with the relative supporting sub-layer. The work elements are then worked in conventional fashion, as necessary, to obtain the desired circuits.
Therefore, the holes are made and the circuits printed on and in said work elements, since the supporting sub-layer is always solidly applied on the print support.
The work element is handled, centered, controlled and stored, always in this reciprocal condition. When the work element has to be combined with other work elements in the desired order, a short time before this combination, the supporting sub-layer is detached from the print support.
During this detachment step and until assembly, the print support is kept in a defined geometric position so as not to suffer any deformation. This geometric position is obtained by means of a plate, advantageously flat, by means of which a desired depression is exerted which holds the print support stationary and still, and does not allow it to deform.
The action of detachment, according to the invention, occurs automatically when the print support is already complete and it is ready to be assembled with other print supports so as to form the desired multi-layer circuit.
According to the invention, the detachment occurs while the print support is moving.
According to the invention, gripping means act on the edge of the supporting sub-layer inducing on said edge an action of detachment which detaches the edge of the supporting sub-layer from the print support and then, progressively, the two elements are completely separated.
According to a first embodiment, the first detachment occurs along one edge of the work element.
According to another embodiment, the first detachment occurs in correspondence with a corner of the work element.
According to a first embodiment of the invention, the gripping means are roller means made of material suitable to interact with the material which makes up the supporting sub-layer, thus creating the desired action of detachment.
According to the invention, the roller means cooperate with the plate bearing the work element, and between the two a pre-defined and pre-definable pressure is maintained, which is related to the material which makes up the roller and the material which makes up the supporting sub-layer.
Means to detach the supporting sub-layer from the roller are provided.
According to a first embodiment, the roller is idle and is made to rotate by the reciprocal movement of the roller and the plate bearing the work element.
According to another embodiment, the roller is made to rotate at a tangential speed equal to the speed of reciprocal displacement of the roller and the plate.
Means to clean the roller and/or restore the properties thereof, which allow the roller to create the desired detachment force, are provided.
According to a variant, an adhesive strip cooperates with the surface of the work element consisting of the supporting sub-layer; the adhesive strip is stuck onto the supporting sub-layer and detaches it from the print support.
Said adhesive strip is then wound in a roll with the supporting sub-layers stuck on.
It is within the spirit of the invention to provide means to detach the supporting sub-layer from the adhesive strip before the latter is re-wound; thus the adhesive strip can be re-used.
It is also within the spirit of the invention to provide a strip which is cleaned on each occasion and as necessary, and re-impregnated with adhesive material, so that it is possible to use a continuous strip.
According to another variant, a removing means cooperates with the edge or corner and achieves the detachment of the print support and the supporting sub-layer, then accompanies the supporting sub-layer until the final detachment.